Output devices are used to provide usable output for us, as well as status
about the operation of the PC.
The video display, printer and speaker are examples of output devices.
Video Display
The video display uses data that the CPU puts into a section of memory called video memory. This data is continuously updated and sent to the display at the right rate and in the right order, so that the screen displays images we can read or interpret.
Printer
Most of you have probably used a printer. The PC sends data that you select such as a file or picture to the printer, usually through either a USB or parallel port on the PC.
Speakers
Most PCs come standard with external speakers that plug into the sound card. These speakers play back any audio source that your PC can send to them such as music, voice and status information (beeps), such as those made during start up.
Input/Output (I/O)
There are some ports on the PC that are used to move data out of as well as back into the PC. They are called I/O ports.
- Serial Port - The serial port is an I/O port. It connects to external devices that need to communicate with the PC. Scanners and digital cameras are examples of devices that can connect to the serial port. It is called the serial port because only one bit of information passes across it during each transfer.
- Parallel Port - The parallel port is also an I/O port that is almost always used for output. More often than not a printer connected to it. It's called a parallel port because it moves a byte (8 bits) of data in parallel during each data transfer.
- Universal Serial Bus - The Universal Serial Bus (USB) is a newer higher speed serial I/O port that will eventually replace the serial and parallel ports. It has been appearing in PCs for a relatively short time. Many printers and other external devices are already equipped with USB ports. The USB port on a PC can connect directly to any device with a USB port. It can also connect to a USB Controller which in turn can connect to many devices that have USB ports.